4/11/2016

1

Biogeochemical Cycles and Book

• You will use information from chapter 47 Starr

text, notes and your own research to

complete the Biogeochemical cycle book.

Biogeochemical Cycles• The flow of a nutrient through the

environment- flowing from living- biotic organisms and back to the abiotic portions of

the environment

• In most organisms 95% of the body is made up

of just four elements.

– Oxygen

– Carbon

– Hydrogen

– Nitrogen

https://www.youtube.com/watch?v=al-do-HGuIk&nohtml5=False

Water Cycle

• Water occurs in 3 states (determined by

temperature)

– Solid

– Liquid

– Gas

• Over 70% of the Earth’s surface is covered by

oceans and water is constantly being cycled

between the hydrosphere (water),

atmosphere (air) and lithosphere (land).

EVAPORATION• The suns energy causes the

bonds between water

molecules to break and

evaporate into water vapor

(Liquid � gas)

• Impurities are left behind

(ex: salt)

– This is important because

about 97% of water on Earth is

salt water and only 3% is

freshwater.

Condensation

• When atmospheric temp decreases, water vapor

(gas) changes back into a liquid

• Small water droplets are formed

– clouds

– Fog

– Drops on plants or on the outside of your cup

4/11/2016

2

Precipitation• Tiny water droplets bounce around in a cloud

as they hit each other, stick together and

become larger. As they get heavier eventually

they fall back to Earth

– Rain, freezing rain, sleet, snow, hail

Surface Runoff

• About 1/3 of water that returns

to Earth as precipitation runs off

the surface of the land, down hill

into streams, rivers, lakes and

oceans.

Infiltration/percolation

• Water that soaks into the ground (downward

movement)

• This water can replenish aquifers, which store

large amounts of freshwater.

Transpiration

• Water is absorbed by plant roots, travels up

through the plant and then is evaporated back

into the atmosphere from the plant leaves.

• Water is returned to the atmosphere by plants

Sublimation

• Conversion of solid water into gaseous form

(no liquid form in between)

• When ice and snow change into water vapor

WATERSHED EXPERIMENT

• WATERSHED- any region where precipitation flows

into a single stream/river

• A watershed in the Hubbard Brook Valley of New

Hampshire was experimentally stripped of

vegetation

• All surface water and materials within draining from

watershed was measured

• Removal of vegetation caused a six-fold increase in

the calcium content of the runoff water

4/11/2016

3

Fig. 47-17b, p.854

BeforeAfter

Hubbard Brook Experiment

losses from

disturbed watershed

time of

deforestationlosses from

undisturbed watershed

Figure 47-17

Page 854

DISCUSS WITH A PARTNER

• In what ways could the deforestation affect

the ecology of the area?

Water Use and Scarcity

• Groundwater is naturally stored in soils and aquifers

– Aquifers are used as source of drinking water in US

– Can be contaminated by

• Landfill chemicals, Hazardous waste / sewage /

pesticides, Underground tanks (that leak)

Aquifer Problems

Figure 47-19

Page 855

Meeting Water needs?

• HOW CAN WE FIX THE PROBLEM?

– Desalinization- the removal of salt from seawater

• is expensive and requires large energy inputs

• requires fossil fuels

• Discuss with a neighbor… how can we

meet our water needs?

4/11/2016

4

Carbon Cycle• Carbon moves through the atmosphere and

food webs on its way to and from the ocean, sediments, and rocks

• All living things contain carbon.

– Calcium carbonate (CaCO3) is an important component of animal skeletons, and is found in several kinds of rocks.

– Carbon dioxide (CO2) is an important part of the atmosphere.

• https://www.youtube.com/watch?v=FgEZpX3n5mo

Short Term Cycling of Carbon

• Lets start with Carbon Dioxide = Found in the

atmosphere.

• PHOTOSYNTHESIS:

– Plants and algae use CO2 along with water and solar

energy to produce their own food

– Take the inorganic carbon and convert it into a molecule

of carbon containing glucose (organic)

– 6CO2 + 6H2O + energy from sunlight → C6H12O6 + 6O2

– Now the Carbon is available for all other organisms to

use as a food source

Short Term Cycling of Carbon

• CELLULAR RESPIRATION

– Consumers eat the plants (including

the glucose) and continue the cycle

of carbon.

– Now the Carbon is broken down

• The Carbon can be built into structures

like skin, muscles, bones, bark, cell

membrane labels

• OR is released as CO2 back into the

atmosphere.

C6H12O6 + 6O2 → 6CO2 + 6H2O + energy

Long Term Cycling

– Other glucose molecules are built into the

structures of the organism. They remain there

until the organism dies.

– The animal must decay before carbon is released

back into the environment.

• CARBON IN FOSSIL FUELS

– When the organism is buried and transformed

over millions of year into coal, oil or natural gas

Long Term Cycling

• CARBON IN ROCKS ETC

– Carbon is also used by ocean dwelling organisms

(Calcium Carbonate CaCO3) to make their shells or

reef

– This material can be broken down after organism

dies and ends up as sediment which forms into

rock. SEDIMENTATION

– Carbon in rock isn’t released until organisms break

down the rock, or natural disasters break down

the rock.

Weathering

• Break down of rocks, soils and minerals

through contact with earths atmosphere,

biota and waters.

– Occurs by wind, water and living things interacting

with the rocks and soils!

• Mechanical weathering- erosion

• Chemical weathering- oxidation

• Biological weathering- lichens

4/11/2016

5

Combustion• When any organic material is burned releasing the

Carbon back into the environment (usually as Carbon

Dioxide)

– Fossil fuels, wood, paper, plastics, and cloth (pollutants

are often included in the burning of those listed above)

Carbon in the Oceans

• Most carbon in the ocean is dissolved

carbonate and bicarbonate

• Ocean currents carry dissolved carbon

Greenhouse Effect

• The suns rays (both solar wavelengths and heat

waves) penetrate the atmosphere

– Those waves are both absorbed and reflected.

• Some of the heat escapes back into space but

much of it is trapped by the greenhouse gases

and water vapor

• These actions allow for life on earth.

Greenhouse Gases

• Greenhouse gases including

carbon dioxide, methane, nitrous oxide, water vapor

and ozone impede the

escape of heat from Earth’s surface. As a bonus Ozone

also blocks much of the

harmful UV radiation from the sun!

Figure 47-22, Page 858

Global Warming

Long-term increase in the amount of these

gases correlates with the increasing

temperature in Earth’s lower atmosphere.

Carbon Dioxide Increase• Carbon dioxide levels fluctuate seasonally

• The average level is steadily increasing

• Burning of fossil fuels and deforestation (as

well as human activity) are contributing to the

increase

CARBON DIOXIDE- Human activity, burning of fossil fuels, deforestation

4/11/2016

6

Other Greenhouse Gases

• CFCs - synthetic gases used in plastics and in

refrigeration

• Methane - produced by termites and bacteria

• Nitrous oxide - released by bacteria, fertilizers, and

animal wastes

Chlorofluorocarbons (CFC)- plastic

METHANE- natural gas, rice fields, cattle

emissions

NITROUS OXIDE-denitrifying bacteria,

fertilizers, animal waste Fig. 47-24, p.860

Recorded changes in global temperature between 1880 and

2000

Nitrogen Cycle• Nitrogen is used by living organisms to produce

amino acids and nucleic acids

• Main reservoir is nitrogen gas (N2) in the

atmosphere= 78% Nitrogen (N2 is not in a usable

form for most organisms)

http://www.youtube.com/watch?v=DP24BceOwt8

Nitrogen Cycle

NO3-

in soil

NH3-,NH4

+

in soil

1. Nitrification leaching

nitrogen fixation

leaching

ammonification 2. Nitrification

dentrification nitrogenous wastes,

remains

NO2-

in soil Figure 47-25

Page 860

Nitrogen Fixation

• Plants cannot use

nitrogen gas (N2)

• Nitrogen-fixing

bacteria convert

nitrogen gas into

ammonia (NH3) and

ammonium (NH4)

Ammonification • Bacteria and fungi

carry out

ammonification

– conversion of

nitrogenous

wastes/decay to

ammonia (NH4)

– Ammonia and

ammonium can be

assimilated by

plants!

– Consumers eat

plant and get

Nitrogen ☺

4/11/2016

7

Nitrification • Nitrifying bacteria convert

ammonium (NH4) to nitrites

(NO4-) and nitrates (NO3-)

which are usable by

plants

• Lightening also converts

DENITRIFICATION• A different type of bacteria (denitrifying

bacteria) convert nitrogen compounds back

into gaseous Nitrogen (N2)

Human Effects

• Humans increase rate of nitrogen loss by

clearing forests and grasslands

• Humans increase nitrogen in water and air

by using fertilizers and by burning fossil

fuels

– This can lead to global warming and acid rain

• Too much or too little nitrogen can

compromise plant health

• Acts as a limiting factor in an ecosystem

Leaching

• Removal of materials from rock or soil by

moving ground water, run off, etc.

• Nitrogen is lost from soils via leaching and

runoff

SEDIMENTARY CYCLES:

PHOSPHORUS CYCLE• Phosphorous is essential to living organisms

because it forms part of important life

– Incorporated into molecules such as DNA and RNA.

– Cell membrane and bone formation.

– Metabolic processes involving ATP.

• Phosphorous is not very common in the biosphere, but is found in ROCK and sediment!

PHOSPHORUS CYCLE

• Short term cycling- phosphorus passes

through food webs (bacteria, fungus, plants

and animals) quickly.

– Plants synthesize dissolved phosphates from soil

water � animals eat the plants � Animals loose

phosphates through urine and feces �

Bacterial/fungus release phosphate from organic

waste � return to plants

4/11/2016

8

SEDIMENTARY CYCLES:

PHOSPHORUS CYCLE

• Long term cycling- phosphorus in rock and

sediment on land and in the ocean pass very

slowly

– Rock formations are slowly broken down by

weathering and erosion which deliver ions to

streams and rivers and sea.

– Here they form the continental shelves (Earth’s

crust) which over millions of years may be uplifted

to land again

https://www.youtube.com/watch?v=wdAzQSuypCk&nohtml5=False

SEDIMENTARY CYCLES: PHOSPHORUS CYCLE

• Eutrophication- nutrient

enrichment of any ecosystem that

is otherwise low in nutrients

– Can occur with any nutrient, but main

culprits are nitrogen and phosphorus

– Cause an algal bloom- which kills the

other natural wild life in the area:

• Algae/bacteria use up the dissolved

oxygen in the water,

• Produce toxins that kill the wildlife

• Blocks the sunlight

https://www.youtube.com/watch?v=AvigoZgYbT4